System and method for adaptive machining

ABSTRACT

A method of repair includes removing a deformed portion of a component to define a native component portion and adding a replacement portion to the native component portion. The replacement portion is adaptively machined based on one or more parameters of the native component portion and based on one or more original design parameters of the component.

BACKGROUND

The disclosure relates generally to machining, and more particularly toa system and method for adaptive machining of components such asairfoils.

In many applications, such as aircraft, various parts are built with aparticular shape or contour, for example, for aerodynamics. Throughnormal service, there arises a need to repair components such asairfoils in aircraft applications, for example. With respect toairfoils, damage to a leading edge of the airfoil is one of the mostcommon problems. The leading edge is subject to foreign object damage orerosion after a period of service time. A significant savings can berealized if the damaged blades can be repaired and returned to service.

Conventionally, the repair has been accomplished by machining away thedamaged portion of the airfoils. Welding material was then manuallydeposited over the areas that had been machined away. The component wasthen machined by referencing a nominal model geometry in an attempt toreproduce the originally designed dimensions. Then, the component washand finished, manually machined, in order to put the component in aserviceable condition.

However, there are shortcomings associated with the historical repairmethod. The method requires leaving a significant amount of materialremaining (i.e., stock on) after the machining, which must be removed bya hand finishing process. This is due to the fact that no component, orblade within a component, is exactly at a nominal condition. The manualnature of the hand finishing process increases the cost and processingtime of the repair. Finally, the method results in significant scrap.

BRIEF DESCRIPTION

In accordance with one exemplary embodiment of the present technique, amethod of repair is disclosed. The method includes removing a deformedportion of a component to define a native component portion and adding areplacement portion to the native component portion. The replacementportion is adaptively machined based on one or more parameters of thenative component portion and based on one or more original designparameters of the component.

In accordance with another exemplary embodiment of the presenttechnique, a computer-implemented method is disclosed. The methodincludes receiving actual measurements of a component having anundesirable portion. The undesirable portion includes a deformation, adamaged portion, an undesirable shape, or a combination thereof. Acomputer model of the component is transformed based on the actualmeasurements and an original design intent, a new optimized design, or acombination thereof.

In accordance with another exemplary embodiment of the presenttechnique, a method of operating an adaptive machining system used formachining a component having a native component portion is disclosed.The method includes measuring a first set of points on the nativecomponent portion. An initial position of a computer model of thecomponent is determined by rigid body transformation using the first setof points measured on the native component portion to form a transformedcomputer model. A second set of points is created on the transformedcomputer model. The second set of points on the transformed computermodel corresponds with the first set of points on the native componentportion. The transformed computer model is morphed by matching the firstset of points with the second set of points.

In accordance with another exemplary embodiment of the presenttechnique, a method of operating an adaptive machining system used formachining a component having a native component portion is disclosed.The method includes creating a set of points in a built-up region of atransformed computer model representative of the native componentportion. The method also includes applying a rigid body transformationand morphing to a plurality nominal cutter contact points of a nominaltool path so as to match the nominal cutter contact points with the setof points to form a plurality of deformed cutter contact points; whereinthe plurality of deformed cutter contact points form a deformed toolpath.

In accordance with another exemplary embodiment of the presenttechnique, a computer program to enable a controller operating anadaptive machining system for machining a component having a nativecomponent portion is disclosed. The computer program includesprogramming instructions stored in a tangible medium that enable thecontroller to receive actual measurements of a component having anundesirable portion. The undesirable portion includes a deformation, adamaged portion, an undesirable shape, or a combination thereof. Thecomputer program also includes programming instructions stored in atangible medium that enable the controller to transforming a computermodel of the component based on the actual measurements and an originaldesign intent, a new optimized design, or a combination thereof.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a diagrammatical representation of a system for machining acomponent, for example an airfoil in accordance with an exemplaryembodiment of the present technique;

FIG. 2 is a diagrammatical representation of a component surface havinga warp patch and rigid patch in accordance with an exemplary embodimentof the present technique;

FIG. 3 is a diagrammatical representation of nominal cutter contactpoints and morphed cutter contact points generated by an adaptivemachining system in accordance with an exemplary embodiment of thepresent technique;

FIG. 4 is a diagrammatical representation of a flow chart illustratingexemplary steps involved in adaptive machining in accordance with anexemplary embodiment of the present technique;

FIG. 5 is a diagrammatical representation of a flow chart illustratingexemplary steps involved in adaptive machining used for machining anairfoil in accordance with an exemplary embodiment of the presenttechnique.

DETAILED DESCRIPTION

As discussed in detail below, embodiments of the present techniqueprovide a method for repairing a component, for example, an airfoil. Themethod includes removing a deformed portion of a component to define anative component portion. A replacement portion is added to the nativecomponent portion. The replacement portion is adaptively machined basedon one or more parameters of the native component portion and also oneor more original design parameters of the component. Other embodimentsinclude a computer-implemented method, a tangible medium includingcomputer-readable or machine-readable code, and a method of operating anadaptive machining system configured to repair a component based on atleast in part on an original design intent, an optimum design, or acombination thereof, as well as present measurements (e.g., dimensions)of the component undergoing repair. In one embodiment, the exemplarytechnique is applicable to a manufactured component having anundesirable shape, e.g. an airfoil with a blunted leading edge.

The exemplary embodiments provide a technique for defining and machiningthe final shape of a repaired part. The exemplary technique employs ageometric model of the component. This model may be a CAD model orgeometry constructed from a library of measurement data. In oneembodiment, the model may be a mesh model. The exemplary techniqueextrapolates information from measured points on the component andcomputer model to obtain a smooth “as-is” shape of the component. Aninitial position for the computer model is determined using a rigid bodytransformation computed using points measured on a surface of the nativecomponent portion. This provides an initial preferred location andorientation for shaping the newly added replacement portion. Thetransformed model geometry is then deformed using a function or processto smoothly blend the native component portion with the replacementportion. Actual tool paths or other processing steps are then derivedfrom either the new geometry, or through the application of the rigidbody transformation and the deformation process directly to nominal toolpaths or process parameters. The shape attributes for the replacedportion may be easily controlled by the user, allowing optimization andcustomization of the machining process. Specific embodiments of thepresent technique are discussed below referring generally to FIGS. 1-5.

Referring to FIG. 1, an exemplary adaptive machining system 10 used formachining a component 12 such as, for example, an airfoil of an aircraftengine, is illustrated in accordance with certain embodiments of thepresent technique. The system 10 includes a measurement system 14configured to provide a first set of measurement points 16 on thecomponent 12 having an undesirable portion. The undesirable portionincludes a deformation, a damaged portion, an undesirable shape, or acombination thereof. It should be noted herein that the measurementpoints 16 are in the “x, y, z” coordinate system and is referred to asthe “measured coordinate system”. The measurement system 14 may includebut not limited to a 5-axis milling machine, coordinate measuringmachine (CMM), an x-ray scanning machine, an optical scanning machine,or an ultrasound scanning machine. The system 10 also includes acomputer model 18 (e.g., CAD model) of the component. The computer model18 of the component is representative of the component geometry, shape,appearance, or a combination thereof, after undergoing a particularmachining operation. The computer model 18 includes a second set ofpoints in the “X, Y, Z” coordinate system and is referred to as the“computer model coordinate system”.

A computer 20 receives the first set of measurement points 16 and thecomputer model 18. The computer 20 is configured to determine thedeviation between the first set of measurement points 16 on thecomponent 12 and the second set of points of the computer model 18. Thecomputer 20 classifies the first set of measurement points 16 on thecomponent as “rigid patch” and “warp patch”. Warp patch may be referredto as a region proximate to a repair zone of the component and rigidpatch may be referred to as region away from the repair zone of thecomponent. Rigid patch and warp patch are explained in greater detailwith reference to subsequent figures below. The computer 20 generates atransformation model that approximates the deformation of the measuredcomponent 12 relative to the rigid patch. The computer 20 may be ageneral purpose computer such as a work station, a personal computer, ora machine controller. The computer 20 includes a processor 22 and amemory 24 including a random access memory (RAM), read only memory (ROM)and/or other components. The computer also includes a monitor 26, akeyboard 28, and a mouse device 30. The computer 20 operates undercontrol of an operating system stored in the memory 24 to present datasuch as the set of measurement points 16 and the computer model 18 to anoperator via the display screen of the monitor 26 and to accept andprocess commands from the operator via the keyboard 28 and the mousedevice 30. The computer 20 generates the transformation model using oneor more computer programs or applications (e.g., code or instructions)through a graphical user interface. Set forth below is a more detaileddiscussion of how the computer 20 generates the transformation model. Acomputer-readable medium, e.g., one or more removable data storagedevices 32 or a fixed data storage device 34, store the operatingsystem, software applications, and other code configured to carry outthe embodiments discussed in detail below. The storage devices 32 and 34may include removable media drives and/or removable storage media, suchas floppy discs, compact discs, digital video discs, flash memory, USBpen drives, and so forth. The storage devices 32 and 34 also may includehard disk drives.

The system 10 also includes nominal tool paths 36 for operating aparticular tool for machining the component 12. After generating thetransformation model, the computer 20 modifies the nominal tool paths 36to the measured coordinate system of the component 12 according to thetransformation model. Set forth below is also a more detailed discussionof how the computer 20 modifies the nominal tool paths 36. Themodification of the nominal tool paths 28 results in deformed tool paths38. A milling controller 40 uses the deformed tool paths 38 to processthe component 12 by single pass machining or multi-pass machining.

Referring to FIG. 2, this figure is a diagrammatical representation of acomponent surface 42 of the component 12 having a native portion 44 anda built-up portion 46 in accordance with an exemplary embodiment of thepresent technique. In the illustrated embodiment, the component 12 is anairfoil. The airfoil is used only for illustration of the disclosedembodiments, which are not limited to any particular type of componentor application. The exemplary technique is equally applicable for repairapplications of other suitable components.

Repairing service parts (such as airfoils) often includes removingdamaged sections of the part to produce a “native” part, and thenreplacing the damaged sections with either weld build-up or some othermetallic substitute that may be machined away to produce a repaired partby smoothly blending the native part with the built-up part. Smoothblending of the repaired part includes accounting for rigid body errorsin the original native part's shape or position, change in part geometrydue to service, and any local warping induced by heating the nativematerial during build up processes. The exemplary embodiments enableusers to maintain or approach design intent, or to optimize their designbased upon the shape of native (remaining) portion of the part beforerepair.

The measurement system 14 is used to measure a first set of points 16 onthe outer surface of the native portion 44 of the component 12. Thecomputer model 18 is registered to the measured first set of points 16on the native portion 44 of the component 12. It should be noted hereinthat image registration may be referred to as a process of transformingdifferent sets of data into one coordinate system. Registration isrequired in order to be able to compare or integrate the data obtainedfrom different measurements. The computer model 18 is subjected to rigidbody transformation and morphing according to the measured first set ofpoints 16. As known to those skilled in the art, rigid bodytransformation may be referred to as a rigid body motion wherein anobject may be moved from one position to another without altering theshape and size. Typical rigid body transformations involve translation,rotation, and reflection. Morphing may be referred to as a techniquethat changes (or morphs) one image into another through a seamlesstransition. The registering, rigid body transforming, and morphing areexplained in greater detail with reference to subsequent flow charts. Inthe illustrated embodiment, the computer 20 initially determines thedeviation between the first set of measurement points 16 on the nativecomponent portion 44 and the second set of points of the computer model18. A rigid patch 48 and a warp patch 50 are identified based on thedeviation between the first set of points 16 on the native componentportion 44 and the second set of points of the computer model 18. Points52 in the region away from the built-up or heated zone 46 (points takenin thicker areas of the part) are referred to as the rigid patch 48.Points 54 proximate to the built-up region 46 (thinner regions of thepart) are referred to as the warp patch 50. The rigid patch 48 providesan estimate of the shape change as well as errors in positioning andorientation of the component 12. The warp patch 50 may change shapesignificantly due to heat and service. Defining relevant patches on thenative component portion 44 and manipulating the patches in a sequence,enables the present technique to obtain a smooth shape and properlydefined features.

Referring to FIG. 3, this figure is a diagrammatical representation ofnominal cutter contact points 56 and morphed cutter contact points 58generated by the machining system in accordance with an exemplaryembodiment of the present technique. In the illustrated embodiment, todefine the final geometry to be machined from the built-up region of thecomponent 12, the computer system 20 creates a set of virtual points ina built-up region 46 of the transformed computer model. The built-upregion 46 of the transformed model corresponds with the built-up orreplacement portion of the component 12. These virtual points may bemanipulated for purposes of matching original design intent or creatingnew optimized shapes at the point of repair or manufacture. The nominaltool path 36 is registered to the set of virtual points on thetransformed computer model. The nominal tool path 36 is then subjectedto rigid body transformation and morphing according to the set ofvirtual points so as to match the nominal cutter contact points 56 ofthe nominal tool path 36 with the set of virtual points of thetransformed computer model to form the plurality of morphed or deformedcutter contact points 58. The plurality of deformed cutter contactpoints 58 form a deformed tool path. The registering, rigid body,transforming, and morphing are explained in greater detail withreference to subsequent flow charts. In some exemplary embodiments, thenominal cutter contact points 56 may be offset from the set of virtualpoints of the transformed computer model to form the deformed cutterpoints 58 of the deformed tool path so as to matching design intent orcreating new optimized shapes at the point of repair or manufacture. Insome embodiments, the original design including geometry and/ordimensions of the component 12 may be adjusted based on actualmeasurements of the native component portion.

Referring to FIG. 4, this figure is a flow chart illustrating oneexemplary embodiment of steps involved in adaptive machining In theillustrated embodiment, the measurement system 14 generates a first setof measurement points 16 on the native component portion as representedby the step 60. The computer 20 receives the first set of measurementpoints 16 from the measurement system 14 and the computer model 18 ofthe component. The computer 20 then determines the deviation between thefirst set of measurement points 16 on the native portion and the secondset of points of the computer model 18 as represented by the step 62.The computer 20 classifies the first set of measurement points 16 on thecomponent 12 into rigid patch 48 and warp patch 50 as represented by thestep 64. The rigid patch 48 and warp patch 50 are identified based onthe deviation between the first set of points 16 on the native portionand the second set of points of the computer model 18.

The computer model 18 is then registered to the first set of measurementpoints 16. The computer model 18 is subjected to rigid bodytransformation and morphing according to the rigid patch 48 asrepresented by the step 66. The method further includes creating a setof corresponding points to drive morphing. In other words, each of themeasured points 16 on the native portion 44 (in both rigid and warppatches 48 and 50) is matched with the closest point on the registered(transformed) computer model 18 as represented by step 70. Transformingthe computer model 18 in the warp patch 48 includes creating a set ofvirtual points in the transformed model that are adjustable to achieveoriginal design intent, new optimized design, or a combination thereof.The registering and rigid body transformation details are described inthe subsequent paragraph.

In the illustrated embodiment, the computer 20 obtains a series of n (x,y, z) points measured on the native component portion 44. The computer20 then generates a series of n pairings between the computer model 18(X, Y, Z) points and the n series of measured (x, y, z) points 16 on thenative component portion 44. Each of the n pairings between the computermodel 18 and the measured series of n points 16 substantially correspondto each other. After generating the series of n pairings between thecomputer model 18 points and the measured points 16 on the nativecomponent portion 44, the computer 20 determines a plurality of mappingfunctions for mapping point locations from the computer model 18 toapproximate measured locations of points on the native component portion44. Mathematical functions such as polynomial functions, trigonometricfunctions or logical functions may be used as the mapping functions. Thecomputer 20 optimizes the mapping functions to minimize the distancebetween the point locations of the computer model 18 to the measuredlocations of points 16 on the native component portion 44. Suitablemathematical functions may be used as the optimization function. Afteroptimizing the mapping functions, the computer 20 then transforms thepoint locations from the computer model 18 to the measured locations ofpoints 16 on the native component portion 44. In particular, theoptimized functions act as basis functions to transform the computermodel coordinates and vectors to reflect the deformations measured inthe native component portion 44. The transformation enables the originalset of computer model 18 points to reside on or substantially near theactual measured points 16. The computer 20 generates a tensor for morphusing the transformed computer model points as represented by the step70. A tensor may be referred to as a generalized linear ‘quantity’ or‘geometrical entity’ that can be expressed as a multi-dimensional arrayrelative to a choice of basis of a particular space on which it isdefined.

Rigid body transformation is applied to cutter contact (CC) points ofthe nominal tool path 36 as represented by the step 72. In other words,after transforming the computer model 18 according to the nativecomponent portion 44, the computer 20 modifies the nominal tool paths 36to the measured coordinate system of the native component portion 44according to the transformed computer model. The nominal tool paths 36include a plurality of points and vectors in the nominal modelcoordinate system. After obtaining the nominal tool paths 36, thecomputer 20 then obtains the optimized mapping functions. The computer20 applies the optimized mapping functions to the nominal tool paths 36.The nominal tool path 36 is registered to the set of virtual pointscreated on the transformed computer model. In particular, for each pointand vector that includes the nominal tool paths 36, the mappingfunctions move the tool path into an appropriate orientation andposition with respect to the transformed model. After applying theoptimized mapping functions to the nominal tool paths 36, the computer20 generates the deformed tool paths. The tensor for morph is generatedaccording to the deformed cutter contact points 58 of the deformed toolpath 38 as represented by the step 74. As discussed previously, in someexemplary embodiments, the nominal cutter contact points 56 may beoffset from the set of virtual points of the transformed computer modelto form the deformed cutter points 58 of the deformed tool path 38 forthe purpose of matching original design intent or creating new optimizedshapes at the point of repair or manufacture. The modification of thenominal tool paths 36 results in the deformed tool paths 38, that thecontroller 40 uses to control a particular machining/manufacturingprocess. The controller 40 then uses the deformed tool paths 38 tomachine the component 12 according to the original deign intent, newoptimized design, or a combination thereof. After machining, themeasurement points 16 on the machined component 12 may again be matchedwith the points on the computer model 18 to check for any deviations forverification purpose as represented by step 78. The exemplary techniquedisclosed herein may be used in a variety of numerical control processessuch as drilling, milling, turning, inspecting, forging, non-contactmeasurement systems, surface finishing systems, or the like.

Referring to FIG. 5, this figure is a flow chart illustrating oneexemplary embodiment of steps involved in adaptive machining usingcomputer software (e.g., code stored on a tangible medium such asmemory). In the illustrated embodiment, a first set of measurementpoints 16 on a native component portion 44 is measured using ameasurement tool. A computer 20 receives the first set of measurementpoints 16 from the measurement tool via a communication port asrepresented by the step 80. The computer 20 also receives a computermodel 18 of the component 12 via the communication port. The computer 20is then used to parse the points data to obtain a points file asrepresented by the step 82. In other words, the computer 20 determinesthe deviation between the first set of measurement points 16 on thenative portion 44 and the second set of points of the computer model 18.The computer 20 classifies the first set of measurement points 16 on thecomponent 12 into rigid patch 48 and warp patch 50.

The computer 20 then runs a registration software program as representedby the step 84. The computer model 18 is registered to the first set ofmeasurement points 16. The computer model 18 is subjected to rigid bodytransformation according to the rigid patch 48. The method furtherincludes creating a set of corresponding points to drive morphing. Inother words, each of the measured points on the native portion 44 (inboth rigid and warp patches 48 and 50) is matched with the closest pointon the registered (transformed) computer model 18. The computer 20 thenruns a tensor program as represented by the step 86. The computer 20generates a tensor for morph using the transformed computer modelpoints.

After transforming the computer model 18 according to the nativecomponent portion 44, the computer 20 then runs a tool pathtransformation program as represented by the step 88. The computer 20modifies the nominal tool paths 36 to the measured coordinate system ofthe native component portion 44 according to the transformed computermodel 18. After applying the optimized appropriate mapping functions tothe nominal tool paths 36, the computer 20 generates the deformed toolpaths 38. The tensor for morph is generated according to the deformedcutter contact points 58 of the deformed tool path 38. The deformed toolpath 38 is then communicated to a machine tool via a communication portfor machining the component 12 as represented by the step 90.

While only certain features of the disclosure have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the disclosure.

1. A computer-implemented method, comprising: receiving actualmeasurements of a component having an undesirable portion, wherein theundesirable portion comprises a deformation, a damaged portion, anundesirable shape, or a combination thereof; and transforming a computermodel of the component based on the actual measurements and an originaldesign intent, a new optimized design, or a combination thereof.
 2. Thecomputer-implemented method of claim 1, comprising identifying deviationbetween the actual measurements and points in the computer model.
 3. Thecomputer-implemented method of claim 1, comprising identifying a rigidpatch and a warp patch on the component based on deviation betweenactual measurements and the computer model.
 4. The computer-implementedmethod of claim 1, comprising registering the computer model to a rigidpatch of actual measurements on the component.
 5. Thecomputer-implemented method of claim 4, wherein registering comprisescreating a rigid body transformation of the computer model at leastgenerally geometrically matched with actual measurements exhibiting lowdeviation relative to the computer model.
 6. The computer-implementedmethod of claim 4, comprising transforming the computer model in a warppatch of actual measurements on the component.
 7. Thecomputer-implemented method of claim 6, wherein transforming thecomputer model in the warp patch comprises creating a set of virtualpoints that are adjustable to achieve the original design intent, thenew optimized design, or a combination thereof.
 8. Thecomputer-implemented method of claim 6, comprising outputtinginstructions for a machine to shape the component at least in theundesired portion according to the original design intent, the newoptimized design, or the combination thereof.
 9. Thecomputer-implemented method of claim 8, comprising executing theinstructions on the machine.
 10. A method of operating an adaptivemachining system for machining a component having a native componentportion, comprising: measuring a first set of points on the nativecomponent portion; determining an initial position of a computer modelof the component by rigid body transformation using the first set ofpoints measured on the native component portion to form a transformedcomputer model; creating a second set of points on the transformedcomputer model; wherein the second set of points on the transformedcomputer model corresponds with the first set of points on the nativecomponent portion; and morphing the transformed computer model bymatching the first set of points with the second set of points.
 11. Themethod of claim 10, wherein measuring the first set of points on thenative component portion comprises dividing the native component portioninto a rigid patch and a warp patch.
 12. The method of claim 11, whereindetermining the initial position of the computer model of the componentcomprises registering the computer model to the rigid patch.
 13. Amethod of operating an adaptive machining system for machining acomponent having a native component portion, comprising: creating a setof points in a built-up region of a transformed computer modelrepresentative of the native component portion; and applying a rigidbody transformation and morphing to a plurality nominal cutter contactpoints of a nominal tool path so as to match the nominal cutter contactpoints with the set of points to form a plurality of deformed cuttercontact points; wherein the plurality of deformed cutter contact pointsform a deformed tool path.
 14. The method of claim 13, comprisingremoving a deformed portion of the component to form the nativecomponent portion.
 15. The method of claim 14, further comprisingreplacing the deformed portion using a replacement portion by joiningthe replacement portion to the native component portion.
 16. The methodof claim 15, wherein the built-up region of the transformed modelcorresponds with replacement portion.
 17. The method of claim 13,wherein morphing the plurality of nominal cutter contact points of thenominal tool path comprises overlapping the nominal cutter contactpoints with the set of points to form the plurality of deformed cuttercontact points of the deformed tool path.
 18. The method of claim 13,wherein morphing the plurality of nominal cutter contact points of thenominal tool path comprises offsetting the nominal cutter contact pointsfrom the set of points to form the plurality of deformed cutter contactpoints of the deformed tool path.
 19. A computer program to enable acontroller operating an adaptive machining system for machining acomponent having a native component portion, the computer programcomprising: programming instructions stored in a tangible medium thatenable the controller to receive actual measurements of a componenthaving an undesirable portion, wherein the undesirable portion comprisesa deformation, a damaged portion, an undesirable shape, or a combinationthereof; and programming instructions stored in a tangible medium thatenable the controller to transforming a computer model of the componentbased on the actual measurements and an original design intent, a newoptimized design, or a combination thereof.